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From:   <gabriel.fernandez@foss.st.com>
To:     Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        Alexandre Torgue <alexandre.torgue@foss.st.com>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Gabriel Fernandez <gabriel.fernandez@foss.st.com>
CC:     <linux-clk@vger.kernel.org>, <devicetree@vger.kernel.org>,
        <linux-stm32@st-md-mailman.stormreply.com>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>
Subject: [PATCH v2 11/13] clk: stm32mp13: add safe mux management
Date:   Fri, 25 Feb 2022 14:31:35 +0100
Message-ID: <20220225133137.813919-12-gabriel.fernandez@foss.st.com>
In-Reply-To: <20220225133137.813919-1-gabriel.fernandez@foss.st.com>
References: <20220225133137.813919-1-gabriel.fernandez@foss.st.com>
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From: Gabriel Fernandez <gabriel.fernandez@foss.st.com>

Some muxes need to set a the safe position when clock is off.

Signed-off-by: Gabriel Fernandez <gabriel.fernandez@foss.st.com>
---
 drivers/clk/stm32/clk-stm32-core.c | 55 ++++++++++++++++++++++++++++++
 drivers/clk/stm32/clk-stm32-core.h |  1 +
 drivers/clk/stm32/clk-stm32mp13.c  | 11 +++---
 3 files changed, 63 insertions(+), 4 deletions(-)

diff --git a/drivers/clk/stm32/clk-stm32-core.c b/drivers/clk/stm32/clk-stm32-core.c
index 69cfa2d1b8e2..d1fe9e5dfdbb 100644
--- a/drivers/clk/stm32/clk-stm32-core.c
+++ b/drivers/clk/stm32/clk-stm32-core.c
@@ -397,6 +397,55 @@ const struct clk_ops clk_stm32_mux_ops = {
 	.set_parent	= clk_stm32_mux_set_parent,
 };
 
+#define MUX_SAFE_POSITION 0
+
+static int clk_stm32_has_safe_mux(struct clk_hw *hw)
+{
+	struct clk_stm32_composite *composite = to_clk_stm32_composite(hw);
+	const struct stm32_mux_cfg *mux = &composite->clock_data->muxes[composite->mux_id];
+
+	return !!(mux->flags & MUX_SAFE);
+}
+
+static void clk_stm32_set_safe_position_mux(struct clk_hw *hw)
+{
+	struct clk_stm32_composite *composite = to_clk_stm32_composite(hw);
+
+	if (!clk_stm32_composite_is_enabled(hw)) {
+		unsigned long flags = 0;
+
+		if (composite->clock_data->is_multi_mux) {
+			struct clk_hw *other_mux_hw = NULL;
+
+			other_mux_hw = composite->clock_data->is_multi_mux(hw);
+
+			if (!other_mux_hw || clk_stm32_composite_is_enabled(other_mux_hw))
+				return;
+		}
+
+		spin_lock_irqsave(composite->lock, flags);
+
+		clk_stm32_set_parent_mux(composite->base, composite->clock_data,
+					 composite->mux_id, MUX_SAFE_POSITION);
+
+		spin_unlock_irqrestore(composite->lock, flags);
+	}
+}
+
+static void clk_stm32_safe_restore_position_mux(struct clk_hw *hw)
+{
+	struct clk_stm32_composite *composite = to_clk_stm32_composite(hw);
+	int sel = clk_hw_get_parent_index(hw);
+	unsigned long flags = 0;
+
+	spin_lock_irqsave(composite->lock, flags);
+
+	clk_stm32_set_parent_mux(composite->base, composite->clock_data,
+				 composite->mux_id, sel);
+
+	spin_unlock_irqrestore(composite->lock, flags);
+}
+
 int clk_stm32_composite_set_rate(struct clk_hw *hw, unsigned long rate,
 				 unsigned long parent_rate)
 {
@@ -515,6 +564,9 @@ int clk_stm32_composite_gate_enable(struct clk_hw *hw)
 
 	clk_stm32_composite_gate_endisable(hw, 1);
 
+	if (composite->mux_id != NO_STM32_MUX && clk_stm32_has_safe_mux(hw))
+		clk_stm32_safe_restore_position_mux(hw);
+
 	return 0;
 }
 
@@ -526,6 +578,9 @@ void clk_stm32_composite_gate_disable(struct clk_hw *hw)
 		return;
 
 	clk_stm32_composite_gate_endisable(hw, 0);
+
+	if (composite->mux_id != NO_STM32_MUX && clk_stm32_has_safe_mux(hw))
+		clk_stm32_set_safe_position_mux(hw);
 }
 
 int clk_stm32_composite_is_enabled(struct clk_hw *hw)
diff --git a/drivers/clk/stm32/clk-stm32-core.h b/drivers/clk/stm32/clk-stm32-core.h
index 61a7b4bb6a19..5a99998c74d9 100644
--- a/drivers/clk/stm32/clk-stm32-core.h
+++ b/drivers/clk/stm32/clk-stm32-core.h
@@ -84,6 +84,7 @@ int stm32_rcc_init(struct device *dev, const struct of_device_id *match_data,
 
 /* MUX define */
 #define MUX_NO_RDY		0xFF
+#define MUX_SAFE		BIT(7)
 
 /* DIV define */
 #define DIV_NO_RDY		0xFF
diff --git a/drivers/clk/stm32/clk-stm32mp13.c b/drivers/clk/stm32/clk-stm32mp13.c
index 783a54e08439..30ecf66f9529 100644
--- a/drivers/clk/stm32/clk-stm32mp13.c
+++ b/drivers/clk/stm32/clk-stm32mp13.c
@@ -359,6 +359,9 @@ enum enum_mux_cfg {
 #define CFG_MUX(_id, _offset, _shift, _witdh)\
 	_CFG_MUX(_id, _offset, _shift, _witdh, MUX_NO_RDY, 0)
 
+#define CFG_MUX_SAFE(_id, _offset, _shift, _witdh)\
+	_CFG_MUX(_id, _offset, _shift, _witdh, MUX_NO_RDY, MUX_SAFE)
+
 static const struct stm32_mux_cfg stm32mp13_muxes[] = {
 	CFG_MUX(MUX_I2C12,	RCC_I2C12CKSELR,	0, 3),
 	CFG_MUX(MUX_LPTIM45,	RCC_LPTIM45CKSELR,	0, 3),
@@ -394,10 +397,10 @@ static const struct stm32_mux_cfg stm32mp13_muxes[] = {
 	CFG_MUX(MUX_UART6,	RCC_UART6CKSELR,	0, 3),
 	CFG_MUX(MUX_USBO,	RCC_USBCKSELR,		4, 1),
 	CFG_MUX(MUX_USBPHY,	RCC_USBCKSELR,		0, 2),
-	CFG_MUX(MUX_FMC,	RCC_FMCCKSELR,		0, 2),
-	CFG_MUX(MUX_QSPI,	RCC_QSPICKSELR,		0, 2),
-	CFG_MUX(MUX_SDMMC1,	RCC_SDMMC12CKSELR,	0, 3),
-	CFG_MUX(MUX_SDMMC2,	RCC_SDMMC12CKSELR,	3, 3),
+	CFG_MUX_SAFE(MUX_FMC,	RCC_FMCCKSELR,		0, 2),
+	CFG_MUX_SAFE(MUX_QSPI,	RCC_QSPICKSELR,		0, 2),
+	CFG_MUX_SAFE(MUX_SDMMC1, RCC_SDMMC12CKSELR,	0, 3),
+	CFG_MUX_SAFE(MUX_SDMMC2, RCC_SDMMC12CKSELR,	3, 3),
 };
 
 struct clk_stm32_securiy {
-- 
2.25.1